A son who felt he had been subjected to years of unfair treatment by his mother and her partner, the millionaire businessman Sir Richard Sutton, took revenge by launching a “ferocious and sustained” knife attack on them at their Dorset mansion, a murder trial has heard. Thomas Schreiber, 35, who was frustrated at having to live with the pair because of a Covid lockdown, killed Sutton, 83, a hotelier and landowner, and inflicted “severe and life-changing injuries” on Anne Schreiber, 66, Winchester crown court was told. The month before the attacks, Schreiber wrote to a friend: “I’m so sad to report that my mind is consumed with hatred of the very worst kind towards my family. They really hurt me, betrayed me and destroyed all trust. Simply put, I contemplate murdering them all morning, day and night. It’s not what I want to think about but it’s the truth. I want them to suffer.” He described his mother as “toxic” and “gold-digging” and said he “couldn’t stand” Sutton and did not have a good word to say about him. Adam Feest QC, prosecuting, said there was no dispute that Schreiber killed Sutton and badly injured his mother, but said the jury would have to consider his state of mind. Schreiber denies murder and attempted murder. The court was told that armed police raced to Sutton’s home on the night of 7 April after a number of people reported that Schreiber had attacked his mother and her partner and was going to take his own life. Police smashed their way in through the conservatory and found Anne Schreiber barely conscious on the floor of the kitchen. She had slash wounds to her face and front and more than 10 wounds to her back. Police carried her out of the house and she was airlifted to hospital, where her life was saved, the jury heard. Officers found Sutton’s “motionless and bloodied body” at the end of the upstairs landing just outside his bedroom. He had five stab wounds under his left armpit, one of which had pierced his heart. Spots of his blood and bloodied footprints were found downstairs in the kitchen, study and pantry. The court was told that after the attack, Schreiber allegedly went to his part of the property, an annexe above a garage, changed some of his clothing, collected personal items and escaped in a Range Rover. He was arrested a few hours later in London after a police chase and a “hard stop” manoeuvre. He had left a kitchen knife with Sutton’s blood on it in an upstairs kitchen sink. Another knife with his mother’s blood on it was found under the kitchen table downstairs. Feest said that in the months before the attack, Schreiber had been harbouring “increasingly strong feelings of resentment and hatred” towards his mother and her partner. The prosecutor said: “Built upon a foundation of many years of feeling isolated and unfairly treated by all his family, and fed by being forced to live at Moorhill [the family home] due to the pandemic – this was the second lockdown period – and the many injustices he felt had been perpetrated against him, these feelings had led the defendant to repeatedly consider revenge and violence.” Feest said: “Whatever it was that started the incident, the defendant attacked Sir Richard and his mother with a knife in the kitchen, perhaps having attacked Sir Richard in the study. This, the prosecution say, is a clear case of murder.” The trial continues.